Brokerage Ills Stir Auditor Scrutiny

U.S. regulators are tightening their scrutiny of accountants in an effort to crack down on firms bungling "red flags" that signal fraud and imperil customer money.

The increased attention is occurring largely at the Commodity Futures Trading Commission, where investigators and top officials were rattled by the collapses of Peregrine Financial Group Inc. and MF Global Holdings Ltd. At both firms, rules that are supposed to...